We often hear that America's young people care about nothing more than selfies and Instagram filters -- that for so many young Americans, the call to service is nothing more than an echo from the past, from a time when being a citizen meant looking beyond one's self.

Yesterday, July 18, was Nelson Mandela Day in nearly every country in the world – a day that asks us to spend time serving others, in the spirit of Mandela himself. Yet for President Clinton, who has been so inspired by Mandela’s life and work, every day...